Highly Efficient Organocatalyzed Conversion of Oxiranes and CO2 into Organic Carbonates

Abstract

The use of a binary catalyst system based on tannic acid/NBu4X (X = Br, I) is presented being a highly efficient organocatalyst at very low catalyst loading for the coupling between carbon dioxide and functional oxiranes affording their organic carbonates in good yields. The presence of multiple polyphenol fragments within the tannic acid structure is considered to be beneficial for synergistic effects leading to higher stabilization of the catalyst structure during catalysis. The observed TOFs exceed 200 h- 1 which is among the highest reported to date for organocatalysts in this area of CO2 conversion. The current organocatalyst system presents a useful, readily available, cheap but above all reactive alternative for most of the metal-based catalyst systems reported to date.